Methods and materials for hydrocarbon recovery

ABSTRACT

Crosslinked polyolefins for use in recovering or containing hydrocarbons such as hydrocarbons contained in oil, are disclosed. Advantageously, the crosslinked polyolefins absorb the hydrocarbon to form a gel that can be collected and processed by heat to release the collected hydrocarbons.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Applicant No.61/375,592 filed Aug. 20, 2010, the entire disclosure of which is herebyincorporated by reference herein.

TECHNICAL FIELD

The present invention relates to polyolefins for use in recoveringhydrocarbons, such as in absorbing hydrocarbons from crude oil orpetroleum products and releasing the recovered hydrocarbons in aseparation process.

BACKGROUND

Effective technology for removing, recovering, and cleaning up oilspills or oil slicks from the surface of sea water and shorelines arestill needed. Typically, the collection of such spills are carried outby applying materials that absorb and/or adsorb the oil. Adsorption isthe adhesion of molecules to the surface of the material and typicallyresults in the oil coating the surfaces (pores and capillaries) of theadsorbent material. Adsorbent materials typically have amicrocrystalline matrix that is not readily penetrated by the oil andtherefore does not swell when adsorbing oil. On the other hand,absorption is the penetration of molecules to the bulk phase of thematerial and typically results in the oil contained within the absorbentmaterial. Affinity between the oil and absorbent material drives oilmolecules into the absorbent matrix. Highly, absorbent materials areusually oil soluble. Cross-linking of such materials is required tomaintain the integrity of the absorbent and prevent its dissolution intothe oil.

There have been some studies reporting the sorption (sorption is thegeneral term for adsorption and/or absorption) of spilled oils withinorganic mineral products (i.e. clay, silica, zeolites, etc.) andorganic vegetable products (straw, corn cob, peat moss, wood fiber,cotton fiber, etc.) (M. O. Adebajo, R. L. Frost, R. L., J. T. Kloprogge,O. Carmody, S. Kokot, “Porous materials for oil spill cleanup: a reviewof synthesis and absorbing properties”, J. Porous Materials, 2003, 10,159-170). Most of these materials show limited oil absorption capacityand also absorb water; therefore the oil absorbers that are recoveredare unsuitable for calcination. Many of these products end-up in landfields after use.

Several synthetic fibers, including crystalline polyethylene andpolypropylene (PP) fibers (U.S. Pat. No. 5,639,541) and meltblownpolypropylene pads and booms (Bayat, et al., Chem. Eng. Technol. 2005,28, 1525) have been disclosed; these materials generally recover oil intheir interstices by capillary action. Because the weak oil-substrateinteraction, the fiber-based sorbers exhibit many disadvantages,including failure to maintain oil of low viscosity, easy re-bleeding ofthe sorbed oil under a slight external force, and poor recovery of oilafter it has sunk in water.

There are patents disclosing the use of synthetic resins, such ascross-linked styrenic and acrylic copolymers, which absorb oil in theirhydrophobic molecular structure. Cross-linking is needed to prevent thepolymer from dissolving in the oils (U.S. Pat. Nos. 5,239,007;5,641,847; and 5,688,843). Such material have the advantage ofselectively absorbing oil floating on the surface of water, and havegood oil-maintaining properties of absorbed oil. However, thesesynthetic resins have the drawback of a long absorbing time incomparison with that of fibers. In particular, they fail to absorb highviscosity oil within a short time. Some methods, i.e. milling the oilabsorber to increase surface area, were proposed to improve the oilabsorbing speed for high viscosity oil, but were met with limitedsuccess. The milled oil absorbers are liable to aggregate, thereby thegel block phenomenon prevents the admission of oil to be absorbed intofurther gaps between the particles of oil absorber.

Further, there are literature reports disclosing the use of cross-linkedstyrene/acrylate (fang, et al., J. Appl. Polym. Sci. 2000, 77, 903),1-octene/acylate (Atta, et al., J. Appl. Polym. Sci. 2005, 97, 80), andoctadecene/maleic anhydride copolymers (Atta, et al., J. Appl. Polym.Sci. 2007, 105, 2113). However, these resins contain some hydrophilicpolar groups and require additional procedures for cross-linkingreaction after copolymerization, and having the drawback of a longabsorbing time, especially for aliphatic hydrocarbon components. Somesynthesized rubbers, such as polybutadiene (Shan, et al., J. Appl.Polym. Sci. 2003, 89, 3309), butyl rubber (Ceylan, et al., Environ Sci.Technol. 2009, 43, 3846), SBR (Fouchet, B., J. Appl. Polym. Sci. 2009,111, 2886), and EPDM (Zhou, et al., J. Appl. Polym. Sci. 2003, 89,1818), were also modified (grafting and cross-linking) to achieve thenetwork structure for oil absorption. However, the solutioncross-linking procedure typically used with such materials is notcontrolled. Moreover, these materials usually require extensive solventextraction to remove any soluble polymer fraction prior to use (Zhou, etal., J. Appl. Polym. Sci. 2002, 85, 2119), and the resulting sol-freematerials possess various degree of cross-linking density that reducesthe overall oil swelling capability. Some methods, i.e. milling,electric-spinning, and foaming of the oil absorbents to increase surfacearea, were applied to improve the oil absorbing speed. However, thesematerials, similar to that of meltblown PP, just physically adsorb oilat the surface by capillary action, and thereby intrinsically preventthe further penetration of oil into matrixes.

Accordingly, there is a continuing need for absorbent materials that canquickly collect and retain hydrocarbons and other such contaminates, asis necessary in the case of oil spills and oil contaminated areas andliquids. Furthermore, there is also a need for absorbent materials thatcan advantageously minimize the treatment of the absorbent after use,including waste disposal, and improve recyclability and biodegradabilityof the recovered absorbent and its contents.

SUMMARY OF THE DISCLOSURE

Advantages of the present invention include polymers, compositions, andmethods for containment, collection, separation and/or recovering ofhydrocarbons, such as a mixture of hydrocarbons contained in oil, froman environment, such as surface water, shorelines, or an enclosedenvironment such as a container or vessel.

An additional advantage of the present invention is a method ofrecovering a hydrocarbon by contacting at least one hydrocarbon or amixture of hydrocarbons, such as contained in petroleum or crude oil,with a crosslinked polyolefin to absorb the hydrocarbon into thecrosslinked polyolefin. Advantageously, the crosslinked polyolefinabsorbs the hydrocarbon to form a gel (i.e., a hydrocarbon-polyolefincomposition) that can be collected and processed by heat to release thecollected hydrocarbon and substantially decompose the crosslinkedpolyolefin, preferably into additional hydrocarbons. The release ofhydrocarbon and decomposition of polyolefin can advantageously becarried out in a typical commercial oil refining process such that thehydrocarbon-polyolefin composition can be treated in more or less thesame manner as an oil feedstock in a refining process.

Additional advantages of the present invention will become readilyapparent to those skilled in this art from the following detaileddescription, wherein only the preferred embodiment of the invention isshown and described, simply by way of illustration of the best modecontemplated of carrying out the invention. As will be realized, theinvention is capable of other and different embodiments, and its severaldetails are capable of modifications in various obvious respects, allwithout departing from the invention. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the attached drawings, wherein elements having thesame reference numeral designations represent similar elementsthroughout and wherein:

FIG. 1 is a schematic representation of a polyolefin according to thepresent disclosure (left) and the corresponding polyolefin gelcontaining absorbed hydrocarbon (right).

FIG. 2 shows data of thermal analyses of certain polyolefins accordingto the present disclosure.

FIG. 3 is a chart showing oil uptake vs. time for certain polyolefins ofthe present disclosure.

FIG. 4 is a chart showing oil uptake vs. time for a polyolefin of thepresent disclosure compared to a commercially available meltblownpolypropylene pad.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure relates to new absorbent polymers, i.e. absorbentcrosslinked polyolefins that can advantageously absorb one or morehydrocarbons, such as hydrocarbons contained in crude oil, petroleumproducts, waste water, or areas containing one or more hydrocarbons.Advantageously the polymers of the present disclosure can simultaneouslyexhibit properties desirable for recovering hydrocarbons from an oilspill, including (a) high oil absorption capacity, (b) fast sorptionkinetics, (c) little to no water absorption, (d) buoyancy for easyrecovery from surface water surface and good mechanical strength, (e)the recovered oil-polymer composition is suitable for use in a typicalcommercial oil refining processes, and (f) cost effectiveness.

The absorbent crosslinked polyolefins of the present disclosure containone or more olefinic monomers with a high affinity for a targethydrocarbon, or mixture of hydrocarbons, and crosslinking units so thatthe polyolefin does not dissolve in the target hydrocarbon. Preferably,the crosslinked polyolefins of the present disclosure contain bothaliphatic and aromatic repeating units as well as the crosslinkingunits. For increased absorption rates, the crosslinked polyolefins havea complete, but lightly cross-linked network structure. The crosslinkedpolyolefins can also have the following independent features, includingan amorphous morphology; a low glass transition temperature (Tg), (asdetermined by differential scanning calorimetry (DSC) described hereinor equivalent equipment and procedures) e.g., a Tg of less than about10° C., such as a low as less than about 0° C. or −10° C.; and a largefree volume.

As a schematic representation of an embodiment of the presentdisclosure, FIG. 1 presents an amorphous polyolefin copolymer structure(left), having high free volume (due to side chains and/or pendantgroups from monomer units) and a network structure (due to thecross-linking of its matrix). The crosslinked polyolefin shown in FIG. 1can rapidly absorb hydrocarbons due the high affinity between thehydrocarbon and/or polymer and/or side chains or pendant groups off ofthe backbone of polyolefin such that the matrix swells its volume toform a hydrocarbon-polyolefin composition (i.e., gel). This structure isshown on the right side of FIG. 1.

In practicing an embodiment of the present disclosure, at least onehydrocarbon, or preferably a mixture of hydrocarbons, such as in crudeoil or a petroleum product, is recovered by contacting the at least onehydrocarbon with a crosslinked polyolefin. Hydrocarbons of particularinterest include, one or more of, or a mixture of aliphatic and aromatichydrocarbons (e.g., alkanes, such as hexane, cyclohexane, heptane,octane; alkenes, such as hexene, heptene, octene; aromatics such asbenzene, toluene, xylene), common petroleum products (e.g., paraffins,naphtha, gasoline, kerosene, diesel, fuel oil, etc.), hydrocarbonscontained in waste water, such as formed through oil recovery process,etc. By this process, the crosslinked polyolefin absorbs the at leastone hydrocarbon to form a gel. Advantageously, the gel comprises thepolyolefin and the hydrocarbon. The crosslinked polyolefin can beoptimized for recovering a particular hydrocarbon or mixture ofhydrocarbons by selecting appropriate olefinic monomers and crosslinkingmonomers to prepare the crosslinked polymer. The crosslinked polyolefincan also include aromatic monomers for increasing the performance of thepolymer to certain hydrocarbon sorption. In one aspect of the presentdisclosure, the hydrocarbon absorption capacity of a crosslinkedpolyolefin is greater than about 10. The absorption capacity as usedherein is determined according to the measurement method describedfurther below. In other embodiments of the present disclosure, thecrosslinked polyolefin has an absorption capacity that is greater thanabout 20, about 30 and even greater than about 40.

In one aspect of the present disclosure, the crosslinked polyolefin isformed from one or more olefins selected from the group consisting of:ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,1-nonene, 1-decene, 3-methyl-1-butene, 4-methyl-1-pentene,3-methyl-1-pentene, 4-methyl-1-hexene, 3,3-dimethyl-1-butene, and4,4-dimethyl-1-hexene, and combinations thereof. The crosslinkedpolyolefin can also be formed from one or more repeating units selectedfrom the group consisting of: styrene, alkylstyrenes, such asp-methylstyrene, o-methylstyrene, m-methylstyrene, 2,4-dimethyl styrene,2,5-dimethyl styrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene andt-butylstyrene, and a combination thereof. Furthermore, the crosslinkedpolyolefin can also be formed from one or more repeating units selectedfrom non-conjugated diene, including 1,5-hexadiene, 1,7-octadiene,1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene,4-propenylstyrene, 4-butenylstyrene, 4-pentenylstyrene,4-hexenylstyrene, and a combination thereof. In another aspect of thepresent disclosure, the crosslinked polyolefin can be formed from about60-95 mole %, e.g., about 60-85 mole %, of one or more alpha olefin,e.g. one or more alpha olefin noted above; from about 5 to 40 mole %,e.g., 15 to 40 mole %, of one or more aromatic monomer, e.g., one ormore aromatic monomer noted above; and from about 0.1 to 3 mole %, e.g.,0.1 to about 2% of one or more crosslinker, e.g. one or more crosslinkernoted above.

Alternatively and separately, the crosslinked polyolefins of the presentdisclosure can be represented by the following formula (I):

wherein (CH₂—CH(R)) represents the same or different olefin repeatingunit, e.g. a C₆-C₃₀ alpha olefin; R is independently H or a C₁-C₃₀linear, branched, or cyclic alkyl moiety; n is an integer greater thanabout 500, e.g., between about 500 and 50,000; (CH₂—CH(Ar)) representsthe same or different aromatic repeating unit, e.g., a styrene unit; Aris an aryl moiety that can be substituted with one or more R₁ groups;wherein R₁ is a C₁ to C₁₀ linear, branched, or cyclic alkyl moiety thatcan be substituted with one or more C₁ to C₅ alkyl groups; p is aninteger in the range from 0 to greater than 50, e.g., 50 to 20,000.Since “p” can be zero it is understood that the crosslinked polyolefindoes not necessarily contain (CH₂—CH(Ar)) units. The variable R₂ iseither present or absent. When R₂ is present, R₂ is a C₁ to C₁₀ linear,branched, or cyclic alkyl moiety that can be substituted with one ormore C₁ to C₅ alkyl groups; X is a cross-linking moiety resulting from athermal induced cycloaddition reaction between two pendent olefinicunits, e.g., a divalent C₄-C₁₈ hydrocarbon unit such as a—CH₂CH₂CH₂CH₂—, or —C₁₆H₁₃— unit; and q is an integer greater than about5, e.g., from about 5 to about 100.

In one embodiment of the present disclosure, (CH₂—CH(R)) represents thesame or different C₆-C₃₀ alpha olefin, e.g., 1-hexene, 1-octene, and1-decene; (CH₂—CH(Ar) represents a styrene monomer, e.g., styrene,p-methylstyrene, and t-butylstyrene; p is an integer greater than about50; (CH₂—CH)—R₂—X—R₂—(CH—CH₂) is formed by the cycloaddition of twopendent styrene units, e.g. between two divinylbenzene units; and theratio of n to p is greater than about 2, e.g., greater than about 3 or4.

In another alternative and separate aspect of the disclosure, thecrosslinked polyolefin can have a long chain branched (LCB) structurewith the following formula (II):

wherein R, n, R₁, p, R₂, q and X are as defined above. Alternatively andseparately, the formula (II) can contain some long chain branches,resulting from chain transfer reaction to the pendent olefin units(after mono-enchainment of non-conjugated diene units) during thepolymerization. The long chain branching number (r) can be zero or thenumber up to about 100. In the case where r is 0, formula (II) is thesame as the formula (I). In each branch, the average number of repeating(CH₂—CH(R)) units (n′) is an integer between 200 and 5,000, and theaverage number of repeating (CH₂—CH(Ar)) units (p′) is an integerbetween 20 and 2,000. The moiety X′ in formula (II) is the residue ofpendent olefinic unit after a chain transfer reaction incorporating aside chain, e.g., a residue formed by chain transfer reaction with apendant styrene unit during the polymerization. In other words, X′ canbe a divalent C₂-C₁₈ hydrocarbon unit in forming the LCB structure.

In each formulae, the crosslinked polyolefin can contain olefinrepeating units selected from the group consisting of: ethylene,propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,1-decene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene,4-methyl-1-hexene, 3,3-dimethyl-1-butene, and 4,4-dimethyl-1-hexene, andcombinations thereof; and pendant aromatic moieties (Ar) selected fromthe group consisting of phenyl, p-methylphenyl, o-methylphenyl,m-methylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl,3,4-dimethylphenyl, 3,5-dimethylphenyl and p-t-butylphenyl, andcombinations thereof.

Further, the crosslinked polyolefins of the present disclosure can alsobe formed by thermal reactions between two or more pendant vinylresidues on the polyolefin chain. They are from one or more repeatingunits selected from non-conjugated diene, including 1,5-hexadiene,1,7-octadiene, 1,2-divinylbenzene, 1,3-divinylbenzene,1,4-divinylbenzene, 4-propenylstyrene, 4-butenylstyrene,4-pentenylstyrene, 4-hexenylstyrene, and a combination thereof. Thevinyl residues can be either linked directly to the chain or with analkyl or aryl spacer. For example, in the formula above, X can be across-linking moiety that is a residue formed by a thermal cycloadditionreaction between two pendant styrene units, e.g., a divalent —C₁₆H₁₃—unit. Alternatively and separately, X can be a cross-linking moiety thatis a residue formed by an addition reaction between pendant olefin unitsor between a styrene unit and a pendent olefin unit. For example, in theformulae above, X′ can be the residue of pendent olefinic unit after achain transfer reaction in forming a LCB structure. An X′ residue with(q)—CH₂—CH₂) unit is formed after chain transfer reaction with a pendantstyrene unit during the polymerization.

In one aspect of the present disclosure, the polyolefin is prepared witha relatively high molecular weight, e.g., M_(w) greater than about100,000 g/mole, preferably greater than about 200,000 g/mole, prior tocrosslinking. Preferably the polyolefin has a relatively narrowmolecular weight distribution (M_(w)/M_(n)) of less than about 4, e.g.,less than about 3, prior to crosslinking. In one aspect of the presentinvention, the polyolefin is crosslinked by heating the material in thebulk phase. For example, pendent styrene units on the polyolefin chaincan be thermally crosslinked in the bulk phase by heating the materialto temperatures of greater than about 220° C. This process fullycrosslinks the polyolefin. The polyolefin can also be thermallycrosslinked by incorporating olefins having pendent vinyl groups tothermally react with one another or other vinyl groups pendent on thepolyolefin chain to form a crosslinked polyolefin. Further, thecrosslinked polyolefin of the present disclosure is preferablycompletely amorphous, i.e., the polymer has only one Tg transition andno detectable melting points (as determined by DSC described herein orequivalent equipment and procedures). Overall, the combination of afacile self-initiated thermal cycloaddition reaction (without anyexternal reagent) and no by-product provides a convenient and economicprocess to prepare the crosslinked polyolefin products.

Polyolefin is an important class of commercial polymers and since theyare prepared from petroleum downstream products, they exhibit manysimilar physical properties with the major components in crude oils.They are also inexpensive polymeric material, with a large productioncapacity around the world. However, crosslinked polyolefins are not incommon use, despite the advantages of crosslinking the polymerstructure, e.g., increasing temperature stability and resistance toelectrical discharge, solvents, creep, and stress-cracking. Mostcrosslinked polyolefins are based on polyethylene (PE) andethylene/propylene/diene elastomer (EPDM) polymers. The commoncross-linking processes, including high energy irradiation (γ-rays andelectron beams), peroxide-induced radical reactions, and silane-moisturecure mechanisms, are not particularly suitable in high alpha-olefinpolymers. This is due to the inherent difficulties that the polymerbackbone exhibits prompt degradation under free radical conditions, andcatalyst poisoning during the transition metal mediated copolymerizationof the cross-linkable silane-containing comonomers. In addition, most ofthe crosslinked polyolefin products do not have a complete networkstructure. That is, the gel content (insoluble fraction after solventextraction) is generally below 90%. Recently, we have reported aneffective bulk (solid state) crosslinking process (Lin et. al.,Macromolecules 2009, 42, 3750), involving a polypropylene (PP) copolymerthat contains a few percentage of pendent styrene groups. Under elevatedtemperature (>160° C.), the pendent styrene units spontaneously engagein regiospecific [2+4] inter-chain cycloaddition reactions between twoadjacent styrene units to form a complete 3-D network, even with a verylow concentration of styrene units. Under the solid state condition,with highly entangled polymer chains and facile coupling reaction,offers convenient crosslinking chemistry. In addition, this selfcross-linking process results in a complete crosslinked polypropylenenetwork with high purity and essentially free of contaminants.

Preferably, the crosslink density and hydrocarbon affinity of thepolyolefins of the present disclosure are optimized such that thecrosslinked polyolefin absorbs a target hydrocarbon to the maximumextent for the particular application. For example, a lowercross-linking density results in higher degree of swelling. Polyolefinsprepared from one or more alpha olefin monomers having a pendanthydrocarbon moiety, such as 1-octene and 1-decene, are similar to thepetroleum downstream products in refining crude oil and have similarsolubility parameters (oleophilic and hydrophobic properties) as thehydrocarbon components in crude oil. The use of aromatic monomers, e.g.,styrenes, with the alpha olefin monomers can further increase theaffinity of crude oil to the polyolefin.

Thus, for the application of recovering crude oil from the environmentsuch as crude oil in an open water environment, the polyolefin should belightly crosslinked and prepared with olefin monomers with at least oneC₆-C₃₀ alpha olefin, with or without aromatic monomers. The combinationof strong affinity of the oil to the olefinic monomers, open amorphousmorphology (high free volume) due, in part, to the use of relativelylong chain olefins, which form branched pendant groups from the mainpolymer chain, and, if present, aromatic pendant groups, and lightcross-linking, allow oil diffusion in such a polyolefin matrix with fastkinetics. Such crosslinked polyolefins can rapidly expand its matrix andachieve high oil absorption capacity and retention. In this embodiment,the oil molecules are captured inside the polymer matrix, with minimalor even completely without water absorption. The resultingpolyolefin/oil composition can float on the water surface with goodstability even after long exposure to air, and with minimal re-bleedingof the absorbed oil under waves or during the recovery operation.

Use of such material can be applied directly to the top of the leakingwell head or oil slick or on an oil contaminated shoreline to form a gelthat floats and can be readily collected and removed to mitigatepollution of water and air by an oil spill.

In addition to effective oil recovery, the resulting gel can be treatedas crude oil, suitable for regular refining processes (distillation andcracking). In practicing an embodiment of the present disclosure,hydrocarbon can be separate from a crosslinked polyolefin gel by heatingthe crosslinked polyolefin containing the at least one hydrocarbon. Inone aspect of the present disclosure the oil loaded crosslinkedpolyolefin gel contains little to no water and has a composition similarto the original crude oil. During refining the gel, the minor componentof the gel, which is the crosslinked polyolefin in about 2 wt % to about5 wt % can be thermally decomposed back to small hydrocarbon moleculeswithout residue.

In another aspect, the crosslinked polyolefins of the present disclosurecan be thermally decomposed back to low molecular weight hydrocarbons,e.g., monomers and other low molecular weight hydrocarbons, at elevatedtemperatures, e.g. from between about 300° C. to about 600° C.Preferably, the crosslinked polyolefins of the present disclosure can bethermally decomposed at temperatures of less than about 500° C., e.g.,between about 300° C. to about 500° C. It is believed that thetemperature used in the first refining or distillation step in a typicalcommercial oil refining process is greater than 600° C.

In one embodiment of the present disclosure, the crosslinked polyolefinabsorbs the hydrocarbon to form a gel (i.e., a hydrocarbon-polyolefincomposition) that can be collected and decomposed by heat to release thehydrocarbon and substantially decompose the crosslinked polyolefin,preferably, into additional hydrocarbons. Preferably, the gel comprisesthe hydrocarbon in an amount that is at least 10 times the amount byweight of the crosslinked polyolefin in the gel, e.g., wherein theamount by weight of hydrocarbon in the gel is ten times or more, such asat least 20, 30 or 40 times the weight of the polyolefin in the gel.

The release of hydrocarbon and decomposition of the crosslinkedpolyolefin can advantageously be carried out in a typical commercial oilrefining process such that the hydrocarbon-polyolefin composition can betreated in more or less the same manner as an oil feedstock in arefining process. For example, FIG. 2 (right) shows the composition ofExample 1 can be thermally decomposed back to small hydrocarbonmolecules without residue well below the typical crude oil refiningtemperature. Therefore, there would be little to no solid wastedisposal.

Therefore, the crosslinked polyolefin-hydrocarbon compositions aresuitable for regular oil refining processes. Thus saving a portion ofthe spilled oil (an economically valuable natural resource), currentlytreated as pollutants to the environments and have the added advantageof minimizing disposal of solid waste and due to the recyclability anddegradability of the crosslinked polyolefins of the present disclosure.

Furthermore, polyolefin products are relatively inexpensive polymericmaterials, with a large production capability around the world. It isestimated that the production cost of crosslinked polyolefins of thepresent disclosure can be below $2 per pound in large-scale industrialproduction. Thus, one pound of crosslinked polyolefin with 40 timesabsorption capacity can recover more than 5 gallons of the spilled oil(currently treated as a pollutant and waste) creating a product worthmore than $12 (based on $80/barrel) and processable as regular crudeoil.

The crosslinked polyolefins of the present disclosure can be prepared byany conventional means. In one aspect of the present disclosure, thepolyolefin can be prepared by a conventional Ziegler-Natta catalystfollowed by thermal crosslinking. Scheme 1 illustrates an examplesynthesis of a crosslinked polyolefin, 1-octene/styrene/divinylbenzene(OS-DVB) terpolymers (a).

In this scheme the crosslinked polyolefin is prepared using aheterogeneous Ziegler-Natta catalyst (i.e. TiCl₃(AA)/AlCl₂Et; where AArepresents an activated by aluminum metal). This traditionalZiegler-Natta catalyst shows effective incorporation of both 1-octeneand styrene co-monomers and mono-enchainment of DVB at ambienttemperature to form the OS-DVB terpolymer with high molecular weight(M_(w)>330,000 g/mol) and quite narrow molecular weight distribution(M_(w)/M_(n)˜2). Basically, the styrene and DVB contents are directlyproportional to the monomer feed ratios. As shown in Table 1, the highOS-DVB terpolymers, containing more than 20 mol % aromatic units(styrene and DVB), have been prepared without any detectablecross-linking reaction. All resulting OS-DVB terpolymers wereprocessable (soluble) for forming various size and shape products (b).However, upon thermal heating (>220° C.) they become completelyinsoluble x-OS-DVB network structure (c) by engaging in a Diels-Alder[2+4] inter-chain cycloaddition reaction between two pendent styreneunits in the adjacent polymer chains. This solid-state crosslinkingreaction (effective and without by-product) can eliminate the need forexpensive solution-removal of hydrocarbon-soluble fraction shown in manyprior arts, in which the crosslinking reactions were usually carried outin dilute solutions with considerable amount of intra-chain couplingreaction.

After the solid-state thermal crosslinking reaction, the resultingx-OS-DVB terpolymers were divided into ¼″ sized particles and subjectedto a vigorous solvent extraction by refluxing in toluene for 36 hours.Any soluble fraction of the resulting x-OS-DVB that was not fullycross-linked into the network structure would have been extracted underthese conditions. The gel % is determined by the weight ratio betweenthe insoluble fraction over the starting x-OS-DVB terpolymer sample.

FIG. 2 shows thermal properties of several x-OS-DVB terpolymer materialsin Table 1, including differential scanning calorimetry (DSC) (FIG. 2 a)and thermogravimetric analysis (TGA) measurements (FIG. 2 b). FIG. 2( a)are DSC curves of four x-OS-DBV polyolefins (Examples 1, 2, 3 and 4 inTable 1). The DSC experiment was carried out on a Perkin-Elmer DSC-7instrument controller with a heating and cooling rate of 20° C./minunder nitrogen. All DSC curves exhibit only one sharp Tg transition inthe flat baselines. There were no detectable melting points up to 200°C. Basically, the Tg (−80° C.) of poly(1-octene) linearly increases withits aromatic comonomer content. All x-OS-DVB terpolymers exhibit verylow T_(g)'s (<−50° C.), even with 25 mol % of the aromatic (styrene andDVB) content. The combination is thus a homogeneous terpolymermicrostructure with completely amorphous morphology with high freevolume. FIG. 2( b) shows TGA curve of an x-OS-DVB sample (Example 1).The TGA experiment was carried out on a TA TGA Q500 instrument with aheating rate of 20° C./min under nitrogen. The x-OS-DVB terpolymerstarts its thermal decomposition at 300° C., and rapidly decreasing itsweight around 400° C. At 450° C., the x-OS-DVB terpolymer was completelydecomposed without any residue, demonstrating the formation of volatilesmall molecules. The bulky side chains weaken the C—C bonds along thebackbone and lower the ceiling temperature.

The resulting x-OS-DVB terpolymers (Examples 1-5 in Table 1) werecontacted with various oils and pure hydrocarbons to show their oilabsorption capability and kinetics. Since crude oil is predominantly amixture of aliphatic and aromatic hydrocarbons with various molecularweights, and the exact molecular composition varies widely fromformation to formation, we decided to examine a broad range of petroleumproducts, including some representative pure aliphatic and aromaticcompounds. Table 1 summarizes the experimental results with severalindividual aliphatic and aromatic hydrocarbons (i.e. hexane,cyclohexane, benzene, and toluene) and some common petroleum products(i.e. gasoline, petroleum, and diesel).

The method for measurement of absorption capacity was carried out byfollowing the standard method (ASTM F726-06) using various oils.Typically, a piece of polymer around 0.2 g was put into gasoline. Aftera certain time after reaching equilibrium, the sample was picked up withtweezers and weighed on a balance. Oil absorption capacity wascalculated by the weight ratio between the absorbed oil to the originaldried material. In order to study swelling kinetics, the abovemeasurements were carried out from time to time. In addition, theabsorption study was also extended to the individual crude oilcomponents, including alkanes (such as heptane), cycloalkanes (such ascyclohexane), and aromatic hydrocarbons (toluene and xylene),respectively.

FIG. 3 also compares the oil uptake vs. time for five x-OS-DVB samples(Examples 1-5 in Table 1) with a crude oil containing about 70% volatilelight oils and 30% non-volatile heavy oils. The oil absorbency andswelling capacity in x-OS-DVB is largely controlled by cross-linkingdensity. They are very minor dependence on the absorbates, eitheraliphatic or aromatic hydrocarbons, or even the mixed oil products. Allx-OS-DVB contain both aliphatic and aromatic side chains with similarmole ratios, but different cross-linking densities. The lowestcross-linking density of x-OS-DVB (Example 1), with 82.3/17.4/0.31-octene/styrene/DVB mol %, exhibits a highest absorbent capacity andswell to a largest degree, which forms a softer and more cohesive gelformation. On the other hand, high cross-link density x-OS-DVB sample(Example 5) shows lower absorbent capacity and swell. The gel strengthis firmer and can maintain particle shape even under modest pressure.

FIG. 4 compares the oil absorption performance of x-OS-DVB sample(Example 1) with a state-of-the-art meltblown polypropylene (PP) padthat is fabricated from a nonwoven fibrous PP textile with highlycrystalline polymer structure and porous morphology (high surface area).The PP pad was obtained from Newpig Corporation in Pennsylvania andindentified as PIG® White Oil-Only Mat Pads & Rolls. The samples wereexamined side-by-side for comparison. The meltblown PP pads (adsorptionmechanism) show rapidly oil adsorption in their interstices by capillaryaction and saturated at the level about 10 times of weight uptakewithout any visible volume enlargement. The adsorption mechanismhappened only on the PP fiber surfaces (not inside the matrix) isadvantage with fast kinetics but limited capacity, and the weak oil-PPinteraction results in some of the adsorbed oil re-bleeding under aslight external force. On the other hand, the lightly cross-linkedcrosslinked polyolefin sample (Example 1) with amorphous morphologygradually absorb oil in its matrix, increasing its weight by more than10 times within 10 minutes, and reaching 40 times after 12 hours. Itsoverall oil sorption capacity is superior (>4 times) to that ofstate-of-the-art meltblown PP pad.

EXAMPLES

The following examples are intended to further illustrate certainpreferred embodiments of the invention and are not limiting in nature.Those skilled in the art will recognize, or be able to ascertain, usingno more than routine experimentation, numerous equivalents to thespecific substances and procedures described herein.

Example 1 Synthesis of 1-Octene/Styrene/Divinylbenzene (OS-DVB)Terpolymer

The polymerization reaction was conducted in a 300 ml stainlessautoclave equipped with a mechanical stirring. The reactor was initiallycharged with 50 ml of toluene, 5 ml of 1-octene (31.9 mmol), 5 ml ofstyrene (43.3 mmol), and 0.2 ml of divinylbenzene (DVB) (1.4 mmol) in anargon filled dry-box. The reactor was then sealed and then moved fromthe dry box and purged with nitrogen gas at 30° C. About 0.101 g ofTiCl₃(AA) and 1 ml of AlCl₂Et in 10 ml of toluene were stirred for about20 minutes and then introduced under nitrogen pressure to the reactor toinitiate the polymerization. After about 3 hours, the reaction wasterminated by adding 100 ml of dilute HCl solution in methanol to thereactor. The polymer was isolated by filtration and was washedcompletely with methanol and dried under vacuum for about 8 hours. About2.79 g of OS-DVB terpolymer was obtained.

The terpolymer was completely soluble in common organic solvents,including toluene and decalin. Its molecular structure was determined bya combination of ¹H-NMR (Bruker AM-300 instrument in chloroform-d) andGPC measurements (Waters 1515 Isocratic HPLC pump with Waters 2414refractive index detector). ¹H-NMR spectrum shows the composition of1-octene/styrene/divinylbenzene mole ratio=87.7/17.4/0.3, and the GPCcurve indicates the terpolymer has a weight average molecular weight ofabout 330 Kg/mol and a polydispersity index (M_(w)/M_(n)) of about 2.1.

Before absorption measurement, the resulting polymer was divided into ½inch size particles and was heated in an oven at about 220° C. for about2 hours to obtain the cross-linked samples. The resulting cross-linked1-Octene/Styrene/Divinylbenzene (x-OS-DVB) terpolymer was subjected to avigorous solvent extraction by refluxing toluene for 36 hours to removeany soluble fraction that was not fully cross-linked into the networkstructure. After drying at 120° C. in vacuum for 8 hours, the insolublex-OS-DVB fraction was weighed to determine the gel content. The gelcontent is a measure of the percent that the terpolymer is crosslinkedand is determined by dividing the weight of the dried and extractedinsoluble x-OS-DVB fraction over the weight of the dried OS-DVB sampleprior to crosslinking. In this experiment, the dried and extractedinsoluble x-OS-DVB fraction weighed 1.5688 g and the dried OS-DVB sampleprior to crosslinking weighed 1.5679 g, resulting in a gel content of99.94%. The results show that the x-OS-DVB terpolymer is fullycrosslinked, i.e., has a gel content of almost 100%.

The resulting cross-linked x-OS-DVB terpolymer (identified as Example 1in Table 1), was subjected to contact with various hydrocarbons bysimple mixing at ambient temperature. A state-of-the-art meltblown PPpad (PIG® White Oil-Only Mat Pads & Rolls from Newpig Corporation inPennsylvania) was also examined side-by-side for comparison. Theabsorption capacity was determined at ambient condition with varioushydrocarbon components contained in crude oil, including hexane, hexane,cyclohexane, benzene, and toluene, respectively, as well as several oilproducts.

The absorption capacity was determined by measuring the weight ratiobetween the absorbed oil to the original dried x-OS-DVB as prepared inExample 1. As an example, a piece of dried x-OS-DVB sample initiallyweighing 0.201 g was dropped into 20 ml of gasoline in a glass bottlewith a sealed cap. After 24 hours, the swelled gel was picked up bytweezers and had a weight of 8.502 g. The weight of thishydrocarbon-polyolefin composition was attributed to 8.301 g of absorbedgasoline and 0.201 g of polyolefin. The absorption capacity wascalculated by dividing the weight of the absorbed hydrocarbon (8.301 g)over the weight of the dried starting material (0.201 g) to obtain anabsorption capacity of 41.3. As shown in Table 1, the x-OS-DVB sample(Example 1) is an exceptional hydrocarbon and oil-absorbent. After 24hours, this cross-linked OS-DVB material swelled and expanded its weightto more than 40 times its dry weight with all aliphatic (linear andcyclic) and aromatic hydrocarbons tested. On the other hand, thecommercial meltblown PP pad showed a comparative adsorption capacity ofabout 10 times or less of its weight.

A sample of x-OS-DVB prepared as described in Example 1 was cut into asquare piece of about a one quarter of an inch in size and thendeposited into a beaker containing water and crude oil (North AmericanLight & Sweet Crude). The starting ¼″ sized sample effectively absorbedthe crude oil from water surface. Upon absorption of the oil, the sampleswelled to about greater than 40 times its initial volume and floated onthe surface of the water as a gel like material. The gel was thencollected by taking the sample off the water surface with a set oftweezers without leaking oil demonstrating a combination of goodmechanical strength (due in part to the crosslinked structure) andstrong affinity between oil and crosslinked polyolefin. It is expectedthat the sample would also be stable under ocean environments (waves,wind, sunlight, etc.) and easy to collect and remove from the watersurface. Use of such material could be applied directly to the top ofthe leaking well head or oil slick or on an oil contaminated shorelineto form a gel that floats and can be readily collected and removed andthus mitigating pollution of water and air.

In addition to the effective oil recovery, the resulting gel can betreated as crude oil, suitable for regular refining processes(distillation and cracking). The oil loaded crosslinked polyolefin gelcontains little to no water and has a composition similar to theoriginal crude oil. During refining the gel, the minor component of thegel, which is the crosslinked polyolefin in about 2 wt % to about 5 wt %can be thermally decomposed back to small hydrocarbon molecules withoutresidue. FIG. 2( b) shows the composition of Example 1 can be thermallydecomposed back to small hydrocarbon molecules without residue wellbelow the typical crude oil refining temperature (>600° C.). Therefore,there would be little to no solid waste disposal. Furthermore,polyolefin products are relatively inexpensive polymeric materials, witha large production capability around the world. It is estimated that theproduction cost of crosslinked polyolefins of the present disclosure canbe below $2 per pound in large-scale industrial production. Thus, onepound of crosslinked polyolefin with 40 times absorption capacity canrecover more than 5 gallons of the spilled oil (currently treated as apollutant and waste) creating a product worth more than $12 (based on$80/barrel) and processable as regular crude oil.

Examples 2-5 Additional Synthesis of OS-DVB Terpolymers

A series of examples were prepared in essentially the same procedure asdescribed in Example 1. Polymerization for Examples 2-5 were carried outin 300 ml stainless autoclave equipped with mechanical stirrer. The samequalities of toluene, catalyst, co-catalyst, 1-octene, and styrene wereintroduced into the reactor as described for Example 1, except agradually increasing divinylbenzene content (0.5, 1, 2.5, and 5 ml) wasused for Examples 2-5, respectively. The increasing amount ofdivinylbenzene used in Examples 2-5 increases the cross-linking densityof the examples. After about 1 hour, the reactions were terminated byadding 100 ml of dilute HCl solution in methanol. The polymers wereisolated by filtration and were washed completely with methanol anddried under vacuum for about 8 hours. The molecular structures (moleratios and molecular weights) of the terpolymers were determined by acombination of ¹H NMR and GPC measurements (Table 1). Samples of theresulting OS-DVB terpolymers were heated at about 220° C. in vacuum ovenfor about 2 hours to obtain cross-linked x-OS-DVB samples. The gelcontent was determined in the manner described in Example 1 and theresults are provided in Table 1.

The absorption capacity data for the various crosslinked samples ofExamples 2-5, respectively, in various hydrocarbons are summarized inTable 1. The absorption capacity was determined in the same manner asdescribed in Example 1.

TABLE 1 Synthesis and hydrocarbon absorption for several x-OS-DVBterpolymers¹ Polymerization Results Monomer Terpolymer Example A/B/C²[A]/[B]/[C]³ Yield M_(w) ⁴ Gel⁵ no. (ml) (mole ratio) (g) (Kg/mol) (%) 15/5/0.2 82.3/17.4/0.3 3.07 330 100 2 5/5/0.5 79.3/20.2/0.5 3.76 410 1003 5/5/1 78.4/20.7/0.9 3.94 420 100 4 5/5/2.5 76.3/22.3/1.4 4.02 460 1005 5/5/5 74.1/24.0/1.9 4.56 520 100 PP⁷ — — — — 100 Absorption capacity(weight ratio)⁶ Example Cyclo- no. Gasoline Petroleum Diesel TolueneHexane Benzene hexane 1 41.3 40.3 41.1 47.1 42.8 40.7 43.5 2 21.1 19.620.0 22.7 20.4 19.8 22.0 3 13.7 11.6 11.9 11.6 11.9 14.1 14.1 4 6.416.28 6.39 6.24 5.62 5.59 7.02 5 5.45 5.34 5.40 4.75 5.10 5.21 5.80 PP⁷9.21 9.71 9.09 10.0 8.10 10.4 11.3 ¹Polymerization condition:TiCl₃(AA)/AlCl₂Et = 0.101 g/4 ml (25 wt % in toluene), 50 ml of toluene,25° C. for 3 h; Cross-linking condition: 220° C. for 2 h. ²A: 1-octene,B: styrene, and C: divinylbenzene. ³Determined by ¹H NMR spectra.⁴Measured by GPC with a standard polystyrene calibration curve. ⁵Afterthermal cross-linking reaction, the gel content was determined from thetoluene-insoluble part after Soxhlet extraction. ⁶Absorption time: 24hours ⁷Commercial meltblown PP pad (obtained from Newpig Corporation)(recovering hydrocarbons via an adsorption mechanism).

FIG. 3 is a plot of crude oil uptake vs. time for the x-OS-DVBpolyolefins of Table 1. The crude oil used in this experiment is knownas North American Light & Sweet Crude. It contained about 70% volatilelight oils and about 30% non-volatile heavy oils. The polyolefins(Examples 1 to 5) of Table 1 have similar 1-octene/styrene mole ratios,but differ in the amount of DVB content and consequently differ incross-linking density. As shown by the data in FIG. 3, the oilabsorbency and swelling capacity in x-OS-DVB polymers are controlled bycross-linking density, i.e., swell capacity is inversely proportional tocrosslink density. That is, as the mole content of DVB in the polymerincreases and consequently the crosslink density increases, theabsorption capacity of the polymer decreases. The lowest densitycross-linked OS-DVB (Example 1, having a mole ratio of 82.3/17.4/0.31-octene/styrene/DVB mol %), exhibits a highest absorbent capacity andswelling. On the other hand, high cross-link density x-OS-DVB terpolymer(Example 5) shows lower absorbent capacity and very little swelling. Thegel strength is firmer and can maintain particle shape even under modestpressure. Example 1 polyolefin absorbed more than 10 times its weightwithin 10 minutes, and absorbed more than 40 times its weight after 12hours. Examples 2 and 3 polyolefins absorbed more than 20 times and morethan 10 times their respective weights in 2-3 hours. After oil uptake,the polyolefin advantageously form a relatively soft and cohesive gel.The oil absorption capacity of the polyolefins provided as Examples 1 to3 are superior to that of commercially available meltblown PP pad interms of overall absorption capacity.

Examples 6-10 Synthesis and Evaluation of 1-Octene/Styrene/1,7-OctadieneTerpolymers

The polymerization reaction was conducted in a 300 ml stainlessautoclave equipped with a mechanical stirrer. The reactor was initiallycharged with 50 ml of toluene, 5 ml of 1-octene, 5 ml of styrene, andvarious quantities of 1,7-octadiene (1.6 ml, 0.8 ml, 0.4 ml, 0.2 ml and0.1 ml) in an argon filled dry-box. The reactor was then sealed and thenmoved from the dry box and purged with nitrogen gas at 30° C. About0.101 g of TiCl₃(AA) and 1 ml of AlCl₂Et in 10 ml of toluene aftersufficiently stirring were introduced under nitrogen pressure toinitiate the polymerization. After about 1 hour, the reaction wasterminated by adding 100 ml of dilute HCl solution in methanol to thereactor. The polymers were isolated by filtration and washed completelywith methanol and dried under vacuum for about 8 hours. The1-octene/styrene/1,7-octadiene terpolymers were completely soluble incommon organic solvents, including toluene and decalin.

Before absorption measurement, the resulting polymers were divided into½ inch size particles and were heated in an oven at about 220° C. for 2hours to carry out a cross-linking reaction. Table 2 provides theabsorption capacity data in toluene after 5 hours and 16 hours. Examples6 to 8 show absorption capacity which is inversely proportional to thecross-linking density. However, Examples 9 and 10, with furtherreduction of cross-linking density, result in some solubility intoluene.

TABLE 2 Summaries of 1-Octene/Styrene/1,7-Octadiene Terpolymers.Absorption In toluene capacity Monomer for 5 h (weight ratio) ExampleA/B/C¹ Yield (weight In toluene No. (ml) (g) ratio) for 16 h 6 5/5/1.63.77 25.81 25.65 7 5/5/0.8 4.46 36.50 36.88 8 5/5/0.4 4.21 42.25 43.88 95/5/0.2 3.60 Partially soluble 10 5/5/0.1 3.42 Partially soluble ¹A:1-octene, B: styrene, and C: 1,7-Octadiene.

As shown in Table 2, sufficiently crosslinked1-Octene/Styrene/1,7-Octadiene polyolefins (B-1 to B-3) can absorb morethan 20 time, 30 time and even 40 times their weight in an aromatichydrocarbon, i.e. toluene, within about 5 hours.

Examples 11-15 Synthesis and Evaluation of1-Octene/t-Butylstyrene/Divinylbenzene Terpolymers

The polymerization reaction was conducted in a 300 ml stainlessautoclave equipped with a mechanical stirrer. In an argon filleddry-box, the reactor was charged with 50 ml of toluene, 0.2 ml of DVB,and various volume ratios of 1-octene and tert-butylstyrene(Oct/BSt=7/3, 6/4, 5/5, 6/4, and 7/3 ml). The reactor was then sealedand then moved from the dry box and purged with nitrogen gas at 30° C.About 0.101 g of TiCl₃(AA) and 1 ml of AlCl₂Et in 10 ml of toluene,after mixing for 20 minutes by stirring, were introduced to the reactorunder nitrogen pressure to initiate the polymerization. After about 1hour, the reaction was terminated by adding 100 ml of dilute HClsolution in methanol to the reactor. The1-octene/t-butylstyrene/divinylbenzene terpolymers were isolated byfiltration and washed completely with methanol and dried under vacuumfor about 8 hours. The resulting terpolymers were completely soluble incommon organic solvents, including toluene and decalin. Beforeabsorption measurement, the resulting terpolymers were divided into ½inch sized particles and heated in an oven at about 220° C. for about 2hours to obtain fully cross-linked samples. Table 3 provides absorptioncapacity data for the samples in toluene after 5 hours and 16 hours.

TABLE 3 Summaries of 1-Octene/t-Butylstyrene/Divinylbenzene TerpolymersAbsorption In toluene capacity Monomer for 5 h (weight ratio) Exam.A/B/C¹ Yield (weight In toluene No. (ml) (g) time) for 16 h 11 7/3/0.25.72 9.84 7.44 12 6/4/0.2 6.69 17.43 25.45 13 5/5/0.2 4.43 35.46 37.4814 4/6/0.2 3.30 28.34 34.81 15 3/7/0.2 2.89 16.50 24.99 ¹A: 1-octene, B:t-butylstyrene, and C: divinylbenzene.

As shown in Table 3, the crosslinked1-Octene/t-Butylstyrene/Divinylbenzene polyolefins can absorb more thanabout 10 times, more than 20 times and even more than 30 times theirweight in an aromatic hydrocarbon, i.e. toluene, within about 5 hours.

Examples 16-19 Synthesis and Evaluation of1-Octene/t-Butylstyrene/1,7-Octadiene Terpolymers

The polymerization reaction was conducted in a 300 ml stainlessautoclave equipped with a mechanical stirrer. In an argon filleddry-box, 50 ml of toluene and various ratios of1-octene/ter-butylestyrene/1,7-octadiene were charged into the reactor.The reactor was then sealed and then moved out from the dry box andpurged with nitrogen gas at 30° C. About 0.101 g of TiCl₃(AA) and 1 mlof AlCl₂Et in 10 ml of toluene after sufficiently stirring wereintroduced to the reactor under nitrogen pressure to initiate thepolymerization. After about 1 hour, the reaction was terminated byadding 100 ml of dilute HCl solution in methanol. The polymers wereisolated by filtration and washed completely with methanol and driedunder vacuum for about 8 hours. The terpolymers were completely solublein common organic solvents, including toluene and decalin. Beforeabsorption measurement, the resulting1-octene/t-butylstyrene/1,7-octadiene terpolymers were divided into ½inch size particles and were heated in an oven at about 220° C. forabout 2 hours to obtain fully cross-linked samples. Table 4 provides theabsorption capacity data for the crosslinked samples in toluene after 16hours.

TABLE 4 Summaries of 1-Octene/t-Butylstyrene/1,7-Octadiene TerpolymersMonomer Absorption capacity Example A/B/C¹ Yield (weight ratio) No. (ml)(g) In toluene for 16 h 16 5/5/0.8 4.08 28.18 17 4/6/0.8 3.53 28.22 183/7/0.8 2.35 29.12 19 3/7/1.6 3.77 19.71 ¹A: 1-octene, B:t-butylstyrene, and C: 1,7-octadiene

As shown in Table 4, the crosslinked1-Octene/t-Butylstyrene/1,7-Octadiene polyolefins can absorb more thanabout 20 times their weight in an aromatic hydrocarbon, i.e. toluene,within about 16 hours.

Example 20 Synthesis and Evaluation of Ethylene/1-Octene/1,7-OctadieneTerpolymer

In a dry Parr 300 ml stainless autoclave equipped with mechanicalstirrer, 75 ml of toluene, 11.8 ml of 1-octene, 0.2 ml of 1,7-octadieneand 5 ml MAO solution (methylaluminoxane, 10 wt % in toluene) were mixedat 60° C. After purging with ethylene gas, about 1 μmol ofrac-Me₂Si[2-Me-4-Ph(ind)₂ZrCl₂] catalyst diluted in 3 ml toluene wasthen syringed into the rapidly stirring solution under ethylene pressureto initiate the polymerization. After 3 minutes of reaction at 60° C.and under 220 psi pressure of ethylene gas, the polymer solution wasquenched with methanol. The resulting product was washed withHCl/methanol (0.5M) and methanol each for 3 times, then vacuum-dried at60° C. About 3.06 g of ethylene/1-octene/1,7-octadiene terpolymer wasobtained with a catalyst activity of 61.2 Kg(PE)/mmol Zr/h. Beforeabsorption measurements, the resulting polymer was subjected to avigorous solvent extraction by refluxing toluene for 36 hours to removeany soluble fraction that was not fully cross-linked into the networkstructure. The soluble fraction was weight to calculate the data of gelcontent (insoluble fraction). The resultingethylene/1-octene/1,7-octadiene terpolymer polymer from this reactionwas not completely cross-linked, with only 40% insoluble fraction, asshown in Table 5.

Examples 21-24 Synthesis and Evaluation ofEthylene/1-Octene/1,7-Octadiene Terpolymers

A series of Ethylene/1-Octene/1,7-Octadiene terpolymers were prepared ina manner similar to the procedure described in Example 20. Thepolymerization reaction was carried out in 300 ml stainless autoclaveequipped with a mechanical stirrer. The same qualities of toluene, MAO,and catalyst were introduced into the reactor as described for Example20 and various volumes of 1-octene and 1,7-octadiene (11.5 ml/0.5 ml, 11ml/1 ml, 10 ml/2 ml, 8 ml/4 ml) were injected to form the sample seriesExample 21 to 24, respectively. The polymerization was quenched withmethanol after 3 minutes of reaction at 60° C. under 220 psi pressure ofethylene gas. The gel content of each resulting terpolymer wasdetermined as discussed in Example 20. Only the fully cross-linkedpolymers were subjected to oil absorption with a small piece of sample(about 0.5 g) at room temperature. In addition, the absorption study wasalso extended into the individual crude oil components, includingalkanes (such as heptane), cycloalkanes (such as cyclohexane) andaromatic hydrocarbons (toluene and benzene). The absorption capacitydata for the various crosslinked samples of Examples 21-24,respectively, in various hydrocarbons are summarized in Table 5.

Example 25 Synthesis and Evaluation of Ethylene/1-Octene/1,7-OctadieneTerpolymer

The procedure Example 20 was followed in a 500 ml stainless autoclaveequipped with a mechanical stirrer. After adding 200 ml of toluene, 11ml of 1-octene, 1 ml of 1,7-octadiene and 5 ml MAO solution underethylene gas, the 1 μmol of rac-Me₂Si-[2-Me-4-Ph(ind)₂ZrCl₂ catalystdiluted in 3 ml toluene was then syringed into the rapidly stirringsolution under ethylene pressure to initiate the polymerization. After 3minutes of reaction at 60° C. under 110 psi pressure of ethylene gas,the polymer solution was quenched with methanol. The resulting productwas washed with HCl/methanol (0.5M) and methanol each for 3 times, thenvacuum-dried at 60° C. About 7.94 g of ethylene/1-octene/1,7-octadieneterpolymer was obtained with catalystic activity of 95.2 Kg(PE)/mmol·h.The gel content and absorption data were determined as the Example 20and are shown in Table 5.

TABLE 5 Synthesis and oil absorption evaluation of ethylene/1-octene/1,7-octadiene terpolymers. Polymerization condition Example1-octene 1,7-octadiene Yield Cat Activity No. (ml) (ml) (g) (Kg/mmol ·h) Gel % 20 11.8 0.2 3.06 61.2 40 21 11.5 0.5 4.24 80.5 76 22 11 1 4.7494.8 100 23 10 2 5.38 108 100 24 8 4 9.51 190 100 25 11 1 7.94 95.2 100Absorption capacity (weight ratio) Example Cyclo- No. Toluene HeptaneBenzene hexane Gasoline 20 — — — — — 21 — — — — — 22 19.5 17.4 17.1 23.218.3 23 15.3 11.1 10.8 19.7 13.5 24 10.2  8.3  8.2 11.8 10.3 25 22.418.1 15.1 29.1 17.1

As shown in Table 5, the crosslinked ethylene/1-octene/1,7-octadienepolyolefins can absorb between about 8 to about 29 times their weight inaliphatic and aromatic hydrocarbons.

In this disclosure there is shown and described only the preferredembodiments of the invention and but a few examples of its versatility.It is to be understood that the invention is capable of use in variousother combinations and environments and is capable of changes ormodifications within the scope of the inventive concept as expressedherein. For example, while the preferred embodiment has been describedas applicable to various surgical joint wounds, the invention would haveuse in other body wounds with minor modifications that would be withinthe skill of the practitioner.

The disclosure provides crosslinked polyolefins effective for absorbinghydrocarbons and examples for their preparation, which includespolymerization using conventional Ziegler-Natta catalyst followed bythermal cross-linking reactions. The combination of oleophilic andhydrophobic properties with amorphous morphology, high free volume, andcross-linked network provides the crosslinked polyolefins advantages forabsorption of crude oil and petroleum products. The oil uptake isinversely proportional to the cross-linking density. Oil uptake with upto more than 40 times of polymer weight and fast kinetics was observedin a lightly cross-linked x-OS-DVB terpolymer. Overall, the crosslinkedpolyolefins of the present disclosure exhibits a combination of benefitsin oil recovery and cleanup, including (i) high oil absorptioncapability, (ii) fast kinetics, (iii) easy recovery from water surface,(iv) little to no water absorption, (v) minimal waste in naturalresources, and (vi) cost effective and economic feasibility. All ofthese advantages can dramatically reduce the environmental impacts fromoil spills.

While the claimed invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to one ofordinary skill in the art that various changes and modifications can bemade to the claimed invention without departing from the spirit andscope thereof. Thus, for example, those skilled in the art willrecognize, or be able to ascertain, using no more than routineexperimentation, numerous equivalents to the specific substances andprocedures described herein. Such equivalents are considered to bewithin the scope of this invention, and are covered by the followingclaims.

Only the preferred embodiment of the present invention and examples ofits versatility are shown and described in the present disclosure. It isto be understood that the present invention is capable of use in variousother combinations and environments and is capable of changes ormodifications within the scope of the inventive concept as expressedherein. Thus, for example, those skilled in the art will recognize, orbe able to ascertain, using no more than routine experimentation,numerous equivalents to the specific substances, procedures andarrangements described herein. Such equivalents are considered to bewithin the scope of this invention, and are covered by the followingclaims.

What is claimed is:
 1. A method of recovering a hydrocarbon, the methodcomprising: contacting at least one hydrocarbon with a crosslinkedpolyolefin, wherein the crosslinked polyolefin absorbs the at least onehydrocarbon and wherein polyolefin has an absorption capacity of atleast
 10. 2. The method of claim 1, the crosslinked polyolefin is formedfrom about 60-95 mole % of an alpha olefin, from about 5 to 40 mole % ofan aromatic monomer and from about 0.1 to 3 mole % of a crosslinker. 3.The method of claim 2, wherein (i) the alpha olefin is selected from thegroup consisting of ethylene, propylene, 1-butene, 1-pentene, 1-hexene,1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-1-butene,4-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-hexene,3,3-dimethyl-1-butene, and 4,4-dimethyl-1-hexene, and combinationsthereof; (ii) the aromatic monomer is selected from the group consistingof styrene, alkylstyrenes, such as p-methylstyrene, o-methylstyrene,m-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene,3,4-dimethylstyrene, 3,5-dimethylstyrene and t-butylstyrene, and acombination thereof; and (iii) the crosslinker is selected from thegroup consisting of 1,5-hexadiene, 1,7-octadiene, 1,2-divinylbenzene,1,3-divinylbenzene, 1,4-divinylbenzene, 4-propenylstyrene,4-butenylstyrene, 4-pentenylstyrene, 4-hexenylstyrene, and a combinationthereof.
 4. A method of recovering a hydrocarbon, the method comprising:contacting at least one hydrocarbon with a crosslinked polyolefin toabsorb the hydrocarbon into the crosslinked polyolefin, wherein thecrosslinked polyolefin has the following formula (I):

wherein (CH₂—CH(R)) represents the same or different olefin repeatingunit; R is independently H or a C₁-C₃₀ linear, branched, or cyclic alkylmoiety; n is an integer greater than 500; (CH₂—CH(Ar)) represents thesame or different aromatic repeating unit; Ar is an aryl moiety that canbe substituted with one or more R₁ groups; wherein R₁ is a C₁ to C₁₀linear, branched, or cyclic alkyl moiety that can be substituted withone or more C₁ to C₅ alkyl groups; p is an integer from 0 to 20,000; R₂is either present or absent and when R₂ is present, R₂ is a C₁ to C₁₀linear, branched, or cyclic alkyl moiety that can be substituted withone or more C₁ to C₅ alkyl groups; X is a cross-linking moiety; and q isan integer greater than
 5. 5. The method of claim 4, wherein (i) theolefin is selected from the group consisting of: ethylene, propylene,1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene,4-methyl-1-hexene, 3,3-dimethyl-1-butene, and 4,4-dimethyl-1-hexene, andcombinations thereof; and (ii) Ar is selected from the group consistingof: phenyl, p-methylphenyl, o-methylphenyl, m-methylphenyl,2,4-dimethylphenyl, 2,5-dimethylphenyl, 3,4-dimethylphenyl,3,5-dimethylphenyl and p-t-butylphenyl, and combinations thereof.
 6. Themethod of claim 4, wherein X is a cross-linking moiety that is a residueformed by thermal cycloaddition reaction between two pendant styreneunits
 7. The method of claim 4, wherein the crosslinked polyolefin iscompletely amorphous.
 8. The method of claim 4, wherein the crosslinkedpolyolefin has a Tg of less than about 10° C.
 9. The method of claim 4,wherein the at least one hydrocarbon is a mixture of hydrocarbons. 10.The method of claim 4, further comprising collecting the crosslinkedpolyolefin containing the at least one hydrocarbon and separating thehydrocarbon from the crosslinked polyolefin.
 11. The method of claim 4,further comprising heating the crosslinked polyolefin containing the atleast one hydrocarbon to separate the at least one hydrocarbon from thecrosslinked polyolefin.
 12. The method of claim 11, further comprisingsubstantially decomposing the crosslinked polyolefin to hydrocarbons.13. A crosslinked polyolefin having the following formula (II):

wherein (CH₂—CH(R)) represents the same or different olefin repeatingunit; R is independently H or a C₁-C₃₀ linear, branched, or cyclic alkylmoiety; n is an integer greater than 500; (CH₂—CH(Ar)) represents thesame or different aromatic repeating unit; Ar is an aryl moiety that canbe substituted with one or more R₁ groups; wherein R₁ is a C₁ to C₁₀linear, branched, or cyclic alkyl moiety that can be substituted withone or more C₁ to C₅ alkyl groups; p is an integer from 0 to 20,000; R₂is either present or absent and when R₂ is present, R₂ is a C₁ to C₁₀linear, branched, or cyclic alkyl moiety that can be substituted withone or more C₁ to C₅ alkyl groups; X is a cross-linking moiety; and q isan integer greater than 5; r is an integer from 0 to 100; n′ is aninteger between 200 and 5,000; p′ is an integer between 20 and 2,000; X′is a branching moiety that is the residue of pendent olefinic unit aftera chain transfer reaction incorporating a side chain.
 14. Thecrosslinked polyolefin of claim 13, where the wherein the crosslinkedpolyolefin has the following formula (I):


15. A gel comprising the crosslinked polyolefin of claim 13 and at leastone hydrocarbon, wherein the hydrocarbon is absorbed in the crosslinkedpolyolefin and wherein the hydrocarbon is in an amount by weight that isat least ten times the weight of the crosslinked polyolefin in the gel.